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There is clear evidence that the Storegga tsunami, triggered by the giant Storegga slide offshore western Norway 8100-8200 years ago, propagated into the Barents Sea. Cores from five coastal lakes along the coast of Finnmark in northern Norway reveal major erosion and deposition from the inundation of the tsunami. The deposits rest on a distinct erosional unconformity and consist of graded sand layers and re-deposited organic remains. Some of the organic remains are rip-up clasts of lake mud, peat and soil and suggest strong erosion of the lake floor and neighbouring land. In this part of the Arctic coastal lakes are usually covered by > 1 m of solid lake ice in the winter season. The significant erosion and deposition of rip-up clasts indicate that the lakes were ice free and that the ground was probably not frozen. We suggest that the Storegga slide and tsunami event happened sometime in the summer season; between April and October. Minimum run-up has been reconstructed to 3-4 m.

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2015 (April): A Holocene sea-level curve and revised isobase map based on isolation basins from near the southern tip of Norway.We report a new Holocene relative sea-level curve based on the stratigraphy in five closely located isolation basins near Lista in southernmost Norway. The results detail the progress and timing of the mid-Holocene Tapes transgression, the peak of which in this region represents the highest postglacial sea level, as well as the rate of land emergence since then. One additional cored basin is situated above the marine limit. All the basins have bedrock sills that were levelled using a differential GPS. Isolation and ingression boundaries were identified by macrofossil analysis and radiocarbon dated on terrestrial plant remains. In most cases several dates were obtained from each transition. Relative sea level rose with a mean rate of 7 mm a −1 during the last part of the Tapes transgression 8600−8200 cal. a BP and then gradually slowed to a mean rate of 1 mm a −1 from 8200−7000 cal. a BP. Mean sea level reached ∼5 m higher than the present level when the transgression culminated. Land emergence took place after this, first slowly at a mean rate of 0.4 mm a −1 until ∼3900 cal. a BP before it increased to 2.6 mm between 3900 and 3400 cal. a BP. Since then it has slowly decreased until today and has been ∼0.2 mm a −1 for the last 2000 years. Based on the new curve we present updated Tapes isobases for the region that are displaced by ∼20 km in relation to the existing model. From one basin we also report a 5-10 cm thick layer of sorted, sandy gravel, embedded in a more than 5-m-thick deposit of homogeneous shallow-marine mud. The gravel was deposited ∼5500 cal. a BP, which is the same age as a tsunami deposit previously mapped in Shetland. As several typical characteristics of tsunami facies deposits are lacking, the origin of the gravel layer remains inconclusive. The age of boundaries between marine and lacustrine segments of the basin stratigraphy signify times when the sea level fell below or rose above the elevation of the bs_bs_banner

Svendsen, J. I. 2010 (January): The first Holocene relative sea-level curve from the middle part of Hardangerfjorden, western Norway. The first relative sea-level (RSL) curve from the mid-Hardangerfjorden area covering the entire Holocene is presented. The curve is based on a series of AMS 14 C dates on terrestrial plant macrofossils across the isolation level in each of five lakes located between 3.5 and 74.5 m a.s.l. During the first 1200 years, the RSL fell very rapidly from the marine limit at 98 m a.s.l. to 33 m a.s.l., i.e. at a rate of 5.4 cm yr À1 . The emergence rate then slowed considerably and was close to standstill 8000-6500 cal. yr BP. However, an emergence of 16.5 m has taken place during the past 6000 years. Radiocarbon dates of terrestrial plant macrofossils from the basal strata in a lake above the marine limit and mollusc shells from glaciomarine silt in the isolation basins yielded a mean age for the local ice-margin retreat of 11 300 cal. yr BP. This verifies that Hardangerfjorden was glaciated during the Younger Dryas -an interpretation that has recently been disputed. The ice margin retreated at a rate of about 300 m yr À1 from the position of the Younger Dryas moraine to this site some 60 km further into the fjord.

Basal records from nine lake basins, located within a small area inside the Younger Dryas Ra moraine in southern Norway, were analysed and radiocarbon dated. Six reworked shell fragments from the lowermost facies in five different basins date to the Bølling–Allerød chronozone and are interpreted to represent an ice‐free coastline before a Younger Dryas ice sheet readvance of at least 8 km. The widespread shell fragments within the Younger Dryas ice margin but pre‐dating the Younger Dryas are demonstrated using a systematic survey of the lowermost strata in a collection of lake basins. A further 13 dated samples, mostly in situ articulated bivalves found in clayey silt overlying the basal facies, yielded overlapping ages close to the Younger Dryas–Holocene boundary. The 13 shell dates, along with two additional similar ages obtained on terrestrial plant macrofossils from basal strata in two basins near the marine limit, provide a minimum‐limiting age of 11.6k cal a BP for ice sheet retreat from the Ra moraine. This suggests that the ice sheet in south‐east Norway retreated from its Younger Dryas maximum position nearly a thousand years later than previously assumed. Similar systematic approaches may lead to improved ice sheet reconstructions from other formerly glaciated coastlines.